Abstract In this paper the hollow cathode effect is discussed in connection with the derivation of some simple laws which relate the current density, j, the gas pressure, p, and the current amplification factor, q. Thus one may conclude that, under the conditions of a fully developed hollow cathode effect, the product I2p does not depend on the gas pressure, and the graph (log q, logp) has a universal slope given by —2·5. In addition, are presented original experimental data obtained in krypton and xenon.